Stadium: M (CC) Round: 25 Ground: Clay
| ITF M15 Oldenzaal | 2021/08/17 07:30 | Nicolas Bruna v Niklas Guttau | 6-3,3-6,6-10 |
| ITF M15 Oldenzaal | 2021/08/16 10:00 | Jordi Garcia Mestre v Niklas Guttau | 4-6,1-6 |
| ITF M15 Oldenzaal | 2021/08/15 08:30 | Egill Sigurdsson v Niklas Guttau | 1-6,4-6 |
| ATP Hamburg | 2021/07/10 09:00 | Carlos Taberner v Niklas Guttau | 6-1,6-2 |
| ITF M15 - Antalya | 2021/04/11 07:00 | Edoardo Graziani v Niklas Guttau | 6-4,6-1 |
| ITF M15 - Antalya | 2021/04/06 07:00 | Niklas Guttau v Edoardo Graziani | 2-6,3-6 |
| ITF M15 - Antalya | 2021/04/05 07:00 | Niklas Guttau v Tomas Lanik | 6-2,6-2 |
| ITF M15 - Antalya | 2021/04/04 06:30 | Niklas Guttau v Michel Hopp | 6-1,6-3 |
| ITF M15 Káhira | 2019/12/14 08:00 | Manuel Guinard v Niels Lootsma | 6-1,6-0 |
| ITF M15 Káhira | 2019/12/13 09:05 | Niels Lootsma v Alex M Pujolras | 4-6,6-3,6-4 |
| ITF M15 Káhira | 2019/12/12 09:00 | Niels Lootsma v Jaime Caldes | 6-2,3-6,6-0 |
| ITF M15 Káhira | 2019/12/11 10:25 | Niels Lootsma v Omar El-Moslemany | 6-3,7-5 |
| ITF M15 Káhira | 2019/12/05 07:30 | Niels Lootsma v Simone Roncalli | 3-6,0-6 |
| ITF M15 Káhira | 2019/12/04 10:25 | Niels Lootsma v Jose Fco. Vidal Azorin | 6-1,6-3 |
| ITF M15 Káhira | 2019/11/27 09:30 | Facundo Juarez v Niels Lootsma | 6-3,6-2 |
| ITF M15 Prague | 2019/11/06 19:35 | Niels Lootsma v Artem Dubrivnyy | 4-6,2-6 |